VINA DEL MAR, Chile—Rafael Nadal says testing for performance-enhancing drugs in sport should strike a balance between catching the cheats and respecting the athletes.

"Not everyone has to pay for some sinners," Nadal said Friday at the VTR Open in Chile.

Nadal said earlier this week that he had passed six blood and urine tests since losing June 28 at Wimbledon. He took seven months off to recover from a left knee injury before returning in Chile.

An 11-time Grand Slam winner, Nadal said it should be made public who is being tested and how frequently.

"If I go through a lot—or very few doping controls—people should know," he said. "Though I went for seven months without competing, I went through a lot of tests."

"I don't have to justify anything," he added. "This information should be open to the public."

All top tennis players are subject to being tested without warning. The admission last month by Lance Armstrong that he used banned substances in all seven of his Tour de France victories has increased the focus on doping in all sports.

"The important thing is that those who are cheating, pay for their cheating," Nadal said. "With Armstrong the image of sport has been damaged, especially in the case of cycling. The important thing is for sport to clean up its image, that the controls are made public.

"They should do the tests they need to do, but they should be done respecting the athlete. From my point of view, this has not always happened.